Smps-2p2z-dspic-description

Collaboration diagram for Smps-2p2z-dspic-description:

Operation:

                                          Wcp0   ( S + Wcz1 )               
  Calculate the transfer function Hc(s) = ---- X ------------------------   
                                           S     ( S + Wcp1 )( S + Wcp2 )   
                                           
    Error Normalization
      ------------
     |   prsft    |
      ------------
Reference   |       e(n)          e(n-1)        e(n-2)
Input       |             --------      --------
        -   -   -        |        |    |        |
  o----|-|-|x|-|x|----o->| z^(-1) |-o->| z^(-1) |-o          Post
        -   -   -     |  |        | |  |        | |         Scaling
        |      NORM   |   --------  |   --------  |
        |             |             |             |          --------
Measured|            ---           ---           ---       |          |     - - - - - - - - - -
Input   |       B0=>| X |     B1=>| X |     B2=>| X |      |posft     |    |                   |
        |            ---           ---           ---       |postScalar|    |     P O W E R     |
        |             |             |             |         ----------     |     P L A N T     |
        |            -------------------------------------        |        |                   |
        |           |                                     | U[n] ---       |                   |
        |           |        A C C U M U L A T O R        |--o--| X |------O Duty Ratio=>PWM  |
        |           |                                     |  |   ---       |                   |
        |            -------------------------------------   |             | Voltage/Current   |
        |             |              |                       |             |      Feedback     |
        |            ---            ---                      |             |         O         |
        |       A2=>| X |      A1=>| X |                     |             |         |         |
        |            ---            ---                      |              - - - - - - - - - -
        |             |              |                       |                      |
        |             |   --------   |  --------             |                      | A/D
        |             |  |        |  | |        |            |                      | Input
        |             o--| z^(-1) |<-o-| z^(-1) |<-----------                       |
        |                |        |    |        |                                   |
        |                 --------      --------                                    |
        |                  u[n-2]        u[n-1]                                     |
        |                                                                           |
        |                                                                           |
         ---------------------------------------------------------------------------
 
   controlHistory[n] = errorHistory[n]   * bCoefficients[0]
                     + errorHistory[n-1] * bCoefficients[1]
                     + errorHistory[n-2] * bCoefficients[2]
                     + controlHistory[n-1] * aCoefficients[0]
                     + controlHistory[n-2] * aCoefficients[1]
 
  where:
 
   aCoefficients[0]  = A1
   aCoefficients[1]  = A2
   bCoefficients[0]  = B0
   bCoefficients[1]  = B1
   bCoefficients[2]  = B2
   controlHistory[0] = u(n)
   controlHistory[1] = u(n-1)
   errorHistory[0]   = e(n) => most recent error {(controlReference) - (sourceRegister)}
   errorHistory[1]   = e(n-1)
   errorHistory[2]   = e(n-2)
   preShift          = prsft    => pre scaling factor for Q15 normalization purposes
   postShift         = posft    => post scaling factor for normalization purposes
   postScaler        = postScaler => post scaling coefficient for normalization purpose
 
   Function call inputs:
   sourceRegister    = ADBUFx  => measured feedback input   
   controlReference  = V_ref    => reference voltage
   targetRegister = PDCx => output duty cycle
 
  where:
 
   aCoefficients, bCoefficients, controlHistory, errorHistory, 
   preShift and postShift are all members of the data structure SMPS_2P2Z_T.
 
 Input:
       w0 = Address of SMPS_2P2Z_T data structure
       w1 = Address of the Source Register (Input)
       w2 = Control Reference
       w3 = Address of the Target Register (Output)
 Return:
       w0 = Address of SMPS_2P2Z_T data structure
       w1 = Address of the Source Register (Input)
       w2 = Control Reference
       w3 = Address of the Target Register (Output)
 
 System resources usage:
       {w4..w5}        saved, used, restored
       {w8,w10}        saved, used, restored
        AccA           used, not restored
        CORCON         saved, used, restored

Note

The function in this assembly file requires CORCON register to be setup in a certain state in order to operate correctly. Due to this requirement, this function will save the CORCON register on the stack in the beginning of the function and restore it before the function return. After saving the CORCON register, this function writes to all bits of the CORCON register. Thus, for the brief duration when this function is executing, the state of CORCON register may be different from its state as set by the function caller. This may change the CPU core behaviour with respect to exception processing latency, DO loop termination, CPU interrupt priority level and DSP-engine behaviour.